AIDS is an infectious disease, which has been known for a few years, is caused by the HIV (HTLV III/LAV, human T lymphotropic virus type III/lymphadenopathy-associated virus), and it leads to death. The destruction of the T helper cells by the AIDS virus must be regarded as causative of the disease. Serious opportunistic infections, such as Kaposi's sarcoma and the so-called AIDS encephalopathy occur as a consequence of the resulting lowered resistance. There has so far not been an effective and tolerated antiviral therapy. One point of attack for such a therapy may be the virus-coded reverse transcriptase, an enzyme, the suppression of which can prevent the further intracellular reproduction of the virus and thus repress its spread in the body. The first clinically tested inhibitors of the HIV revertase, such as Suranim (GERMANIN.RTM.) have not yet attained the necessary tolerance and the hoped-for effectiveness. Only the 3'-azidothymidine (N.sub.3 TdR) (see German Federal Republic patent No. 3,500,606) has unambiguous life prolonging effects in AIDS patients with Pneumocystitis carinii pneumonia. These effects are accompanied by improvements in clinical and neurological findings, as well as by occasional restoration of certain immunological functions (Fischl et al., The New England J. of Medicine 317, 185 (1987)). As against this, the toxic side effects on the bone marrow of the 3'-azidothymidine make blood transfusions necessary in about 50% of the patients and points to the need for more selective inhibitors of the HIV reverse transcriptase; at the same time, their effectiveness should also be increased.